This presentation will be given online by zoom, with the zoom link sent to the AMC seminar list. Participants interested in viewing should sign up for that list (see AMC Seminar website).
On long enough time scales, the Earth mantle (the region between the rigid plates at the surface and the liquid metal outer core at depth) behaves like a fluid. While it moves only a few centimeters per year, the large length scales nevertheless lead to very large Rayleigh numbers and, consequently, very complex and expensive numerical simulations. At the same time, given the inaccessibility of the Earth mantle to direct experimental observation implies that numerical simulation is one of the few available tools to elucidate what exactly is going on in the mantle, how it affects the long-term evolution of Earth's thermal and chemical structure, as well as what drives and sustains plate motion.
I will here review the approach we have taken in building the state-of-the-art open source solver ASPECT (see http://aspect.geodynamics.org) to simulate realistic conditions in the Earth and other celestial bodies. ASPECT is built using some of the most widely used and best software libraries for common tasks, such as deal.II for mesh handling and discretization, p4est for parallel partitioning and rebalancing, and Trilinos for linear algebra. In this talk, I will focus on the choices we have made regarding the numerical methods used in ASPECT, and in particular on the interplay between higher order discretizations on adaptive meshes, linear and nonlinear solvers, optimal preconditioners, and approaches to scale to thousands of processor cores. All of these are necessary for simulations that can answer geophysical questions.
BIO: Wolfgang Bangerth is a professor of mathematics and (by courtesy) of geosciences at Colorado State University. His research is on the numerical solution of partial differential equations and, in particular, the simulation of applied, complex problems described by PDEs. He is the founder and one of the principal developers of the deal.II finite element library (see https://www.dealii.org/) that is used around the world and is the basis for some 1,500 publications in nearly all fields of the sciences and engineering. For its creation, he has received the 2007 Wilkinson Prize. He is also founder and principal developer of the Advanced Simulator for Problems in Earth ConvecTion, ASPECT (see https://aspect.geodynamics.org), and is the Editor-in-Chief of the ACM Transactions on Mathematical Software (TOMS).
Wolfgang received his PhD in 2002 from the University of Heidelberg, Germany. He then was a postdoc at the University of Texas at Austin before becoming a professor first at Texas A&M University and now at Colorado State University.